My friend has 2 small goldfish in a 10G. They've both been doing fine for the past 3-4 weeks since she got them but when she came home today one of them was bent or curved to the left and at first she thought he was dead but then saw he was breathing very slowly. She's very meticulous about her tank and water levels and it doesn't show ammonia but she just (unknowingly) ran out of testing strips so is unable to test other elements. Is this a common ailment perhaps not related to water levels?

if u don't mind me ask but how is this possible for a goldfish 2 be bent and still keep breathing if it couldnt be any trouble could u post a pic about it please

Sorry if this is not my place to post, but I don't think we can get a pic, the fish is dead. The gold fish could have developed a big bulge on the one side which may have made it look bent._________________Years of fish keeping = Good advice